"It was already marvellous. Then there were these two finbacks, one of which passed under the Zodiac without touching the boat."

Mr Mouellic says there was a moment of unease when he thought the whale would strike the boat.

"But it was, in fact, magic," he said.

The boat operator told passengers he had never seen anything like it in 15 years.

The Saguenay-St Lawrence Marine Park, where the video was filmed, is one of the world's top whale-watching sites. Humpbacks, finbacks, minke, North Atlantic right whales and killer whales come to feed in the summer and fall, and beluga whales can be seen in the area year-round.

Finback whales, like the one seen in the video, feed on large schools of fish and krill as deep as 100 metres below the surface. They come up three or four times to breath before diving back down to feed.

Finbacks eat one to two tonnes of fish or krill per day and weigh around 50 tonnes.